1. Field of the Invention
The present invention relates to a wideband and multi-band frequency up converter, and more particularly, to a wideband and multi-band frequency up converter capable of minimizing unwanted spurious components of a radio frequency (RF) signal by using a wideband as a passband of a single secondary filter in a double frequency conversion structure.
2. Discussion of Related Art
With the development of electronic technology, various types of electronic devices or apparatuses have been developed and used, a communication device is one of them.
The communication devices and apparatuses are being used for transmitting and receiving a signal between apparatuses in various fields, and recently, as communication technology rapidly develops, satellite communications are generally used so that a subscriber located in a remote area performs communication through a satellite.
Conventionally, a satellite communication system allows subscribers located in the remote areas to transmit and receive audio or data through a geostationary satellite installed at the height of 36,000 km, a satellite earth station located on the ground uses a high-power and super-high frequency as an uplink signal in order to communicate with the satellite located in the sky, and when a power level of the uplink signal transmitted to the satellite is small, a signal to noise ratio is decreased, reception sensitivity is degraded, or communication is disconnected.
Accordingly, various technologies are being developed in order to increase the power level of a transmission signal of a satellite earth station, and for example, there is Patent Reference 1. However, in order to generate a wideband and multi-band signal of a frequency band over 2 GHz using conventional technology, a plurality of local oscillators and output circuits are connected in parallel, and a switch for selecting a desired band is needed. Accordingly, when generating the wideband and multi-band signal using the frequency up converter (a transmitter) used in the conventional satellite earth station, there are problems in which a circuit becomes complicated and also costs are increased since a size of the satellite earth station transmitter is large.